Abstract: There is disclosed a tool changer apparatus for rapid changing of a tool holder in a mill incorporating a draw bar having a gripper mounted on one end thereof for gripping a holding flange formed in a tool holder so retraction of such draw bar will close the collet on such flange to draw a centering taper formed in such tool holder into mating relationship with a complementary taper formed on one end of the mill spindle to center such holder. Incorporated on the opposite end of such draw bar is a tightener incorporating toggle links for holding the draw bar in its retracted position and operative upon retraction of the mill quill to release such toggle link to thereby extend such draw bar and release the tool holder from such gripper.

Abstract: There is disclosed a motion sensor which may be utilized for sensing rotary motion and incorporating a housing formed with a vertical barrel having pins projecting diametrically inwardly from the opposite sides thereof and terminating in spaced apart relationship. Received telescopically in the barrel between the pins is a cylindrical float formed on its opposite sides with outwardly opening reliefs forming at their upper extremities downwardly concave arches for resting on the pins and each forming a pair of horizontally spaced apart flutes extending downwardly on opposite sides of a vertical rib which terminates at its upper extremity in an upwardly facing abutment surface aligned centrally below such arch for selective engagement with the pins as the float is telescoped upwardly in such barrel.